Log in as admin. Go to an existing course or create one. On the cog, click More... Click on the Question Bank link. Create few questions, can be of any type really (essay is easy to setup). Click the new tag icon. Make sure a modal is displayed, containing the question name, current category context and a tag form field. On the tag field, add a new tag (science for example) and press Save Changes. The page should be reloaded, click on the tag icon again. The tag you have entered must be present (science), now add another tag for this question, let's say (biology) and save. The page should have been reloaded, click on the tag icon. You should see two tags (science and biology) Remove one of those two tags and save. Open the modal again, it should display just one tag. Now remove this tag and save. Open the modal again, you should not see any tags. Now let's test capabilities, in that course, enrol a user with teacher role. Go to course administration > Users > Permissions. Remove moodle/question:editall capability from teacher role. Now log in as that teacher. Go to that course then Course Administration > Question Bank. Make sure you are able to see the tags icon. Click on the icon, make sure you see all the information question name, current category context but the tag field is static and you are not able to add or remove any tags.